Metal seal



39% B. J. WATKINS METAL SEAL 2 Sheets-Sheet 1 Filed July 1, 1963 INVENTOR (fig, W W0 mam/s flrra/zwEy-s- HIQUCE United States Patent 3,288,472 METAL SEAL Bruce J. Watkins, Palos Verdes Estates, Califi, assignor to Regan Forge & Engineering Co., San Pedro, Calif., a corporation of California Filed July 1, 1963, Ser. No. 291,723 3 Claims. (Cl. 277-11) This invention relates in general to an apparatus and method of effecting a fluid tight surface seal between an oil Well drilling casing and an inner casing or mandrel member upon running of the casing over the mandrel member. More particularly, this invention relates to an apparatus and method of effecting such a high pressure metal seal particularly adapted for use in subsea oil well drilling which is deformable within its elastic limit to provide a surface seal between coaxial casing members without the application of additional external or internal sealing forces.

With the increase in off-shore or subsea oil well drilling from stationary platforms and floating vessels, there has developed a need for apparatus and methods of effecting high pressure seals between coaxial casing members capable of use in subsea locations at an appreciable distance from the well rig. Further, in undersea drilling the repeated entry and re-entry of a well for the various drilling and producing operations at water depths of several hundreds of feet has created a demand for a seal that is reusable indefinitely and effected merely upon the running of an outer casing over an inner casing or mandrel member. For example, in drilling a subsea well, after the surface casing has been landed on the conductor pipe casing set in the well, a drilling bonnet is run down over the surface casing head and latched thereto. In order to maintain well pressure within the casing, while drilling the production casing hole, a high pressure seal must be effected between the bonnet and surface casing head, preferably upon the running of the bonnet over the casing head.

Previously employed seals have not been suitable for use in a subsea environment and have not been reusable. Pressurized seals and annular rings of different shapes, fitted together in stacks or nests, have been employed unsatisfactorily. Such seals, made of synthetic rubber, fiber composition and soft metal have all tended to deform permanently on their first use. Prior rubber seals have provided only a lip seal, depended on internal well pressure for sealing forces and deteriorated from the associated gases and the presence of sea water. Prior metal seals, such as disclosed in United States Letters Patent No. 2,766,829 have required the application of external forces, as by clamps and bolted flanges, to effect a seal. Such metal seals incorporated with conduit connections cannot operate to effect a seal on running of a casing member over a mandrel and thus are not suited for use in the repeated engagement and disengagement of mating parts in drilling operations beneath the sea.

It is a primary object of this invention, therefore, to disclose and provide apparatus for and a method of effecting a high pressure metal-to-metal seal between a casing and an inner mandrel member upon the running of the casing over the mandrel member.

It is also an object of this invention to disclose and provide a metal seal assembly adapted to be used in subsea oil well drilling and producing operations which will not deteriorate in the subsea well drilling environment, which is reusable and is easily assembled within an oil well casing to be run over an inner casing or mandrel member.

It is a further object of this invention to disclose and provide a metal seal assembly to be preassembled within a casing which is self-energizing upon running of the cas- "ice ing over the mandrel to effect a fluid tight seal between the casing and a mandrel without the application of additional internal or external forces.

It is another object of this invention to disclose and provide a method of effecting a fluid tight surface seal between a casing and a mandrel member upon running a casing over a mandrel member without the application of internal Well pressures or external clamping pressures to effect the seal which is easily employed on subsea drilling and producing operation and insures repeated use of the sealing apparatus for an indefinitely long period of time.

It is a still further object of this invention to disclose and provide a novel apparatus and method of orienting a metal sealing means within a recess within an oil well casing to unfailingly provide an effective fluid tight surface seal between the sealing means and an inner casing or mandrel member over which the casing is run and insure its retention within the casing upon removal of the casing from the mandrel member.

It is also another object of this invention to disclose and provide a method of spacing a single metal seal ring within a casing recess during its elastic deformation by the passing of a mandrel member therethrough upon the running of a casing member over an inner casing or mandrel member to prevent binding, undue wearing and deterioration of the metal seal ring within the casing.

Generally stated, the apparatus according to the present invention comprises a metal seal assembly including an annular sealing means made of metal with an upwardly opening annular channel therein. The channel is formed by spaced divergent walls having outer surfaces provided with a downward taper, a taper of approximately two degrees in the preferred embodiment. The sealing means is adapted to be inserted within a recess within a casing member with its tapered outer Wall elastically deformed therein and its inner tapered annular wall protruding into the bore of the casing. An annular spacer means is associated with the aforementioned channel to abut portions of the casing recess and portions of the sealing means to space the sealing means from an overhead portion of the recess. Such spacing is provided in accordance with the invention to insure unfailing, reliable operation of the sealing means upon running of the casing over the mandrel member. Also, annular seal retainer means are provided to insure the proper positioning of the spacer means and sealing means within the casing and their retention within the casing upon relative movement between the casing and mandrel member. Two exemplary embodiments of apparatus within the invention will be subsequently described in detail.

Generally stated, the method according to the present invention comprises: the placing of an annular metal spacer ring in a selected location within an internal recess in an oil well casing; press fitting an annular metal sealing ring into the recess over the annular sealing means and elastically deforming an outer wall thereof against a side wall of the casing recess; running the casing, spacer ring and sealing means over an inner casing or mandrel member to provide a fluid tight surface seal through elastic deformation of an inner wall of the sealing means against the mandrel; and concurrently with said running step, spacing the sealing ring from an overhead portion of the recess positioning the sealing ring and insuring uniform elastic deformation of such inner wall. Thereafter, the casing may be backed off of or Withdrawn from the mandrel while retaining the sealing ring within the casing recess ready for the next application of the method.

Further objects and various advantages will become apparent and a better understanding of the apparatus and method of the present invention will be obtained from a consideration of the following detailed description of exemplary embodiments of the metal seal assembly and method of effecting same. Reference will be made to the appended sheets of drawings in which:

FIG. 1 is .a section view of a portion of an oil well drilling casing containing an exemplary embodiment of the metal seal and seal assembly in accordance with the present invention prior to the running of the casing completely over the running mandrel member;

FIG. 2 is a section view of the casing, metal seal and assembly and inner casing or mandrel member of FIG. 1 with the casing run over the mandrel member and the metal seal providing a metal-to-metal surface seal between the casing and mandrel member;

FIG. 3 is a section view of the casing, metal seal and assembly and inner casing or mandrel member of FIGS. 1 and 2 with the casing member being backed off of the inner casing or mandrel member;

FIG. 4 is an exploded view of the exemplary embodiment of metal seal assembly of FIGS. 1 through 3 shown in inverted position prior to its assembly;

FIG. 5 is a section view of an alternative exemplary embodiment of a casing, metal seal assembly according to the invention and inner casing or mandrel member prior to the complete running of the casing over the mandrel member;

FIG. 6 is a section view of the casing, alternative exemplary embodiment of metal seal assembly and inner casing or mandrel member of FIG. 5 with the casing complete-ly run down over the mandrel member;

FIG. 7 is a section view of the casing, metal seal assembly and inner casing or mandrel member of FIGS. 5 and 6 with the casing being backed off of the inner casing or mandrel member; and

FIG. 8 is an exploded view of the alternative exemplary embodiment of metal seal assembly of FIGS. 5 through 7.

Referring first to the exemplary embodiment of a metal seal, according to the present invention, that is shown in FIGS. 1 through 4, a casing 10 and inner casing or mandrel member 11 are shown at the time the casing 10 is being run over mandrel 11, but prior to engagement between the exemplary metal seal, indicated generally at 20, and the mandrel member 11. The metal seal, indicated generally at 20, is pre-assembled within a recess in the casing 10 so that the running of the casing down over the mandrel will bring the metal seal into a metal-to-metal fiuid tight surface seal with the mandrel 11. In the exemplary embodiment of FIGS. l through 4, the recess in the casing 10 which receives the metal seal, indicated generally at 20, is provided by an annular seal retainer means which comprises part of the metal seal assembly in accordance with the present invention. Such metal seal assembly comprises generally an annular sealing means for mounting within a recess within the casing 10, recessed relative to thecasing bore 12; spacer means associated with the sealing means for limiting movement thereof within the recess in casing 10; and an annular seal retainer means for mounting within the casing adjacent the sealing means to retain it withinin the casing during relative movement of the casing 10 and mandrel 11.

Annular sealing means for mounting within a recess within casing 10, recessed relative to the casing bore 12, in the exemplary embodiment of FIGS. 1 through 4 is an annular metal sealing ring, indicated generally at 20 having spaced divergent channel walls 21 and 22 interconnected by a bight portion 23. The outer wall 21 and inner wall 22 with the bight portion 23 form an upwardly opening annular channel within the annular metal sealing ring. The inner surface of the annular metal sealing ring, indicated generally at 20, provided by wall 22 is downwardly tapered preferably approximately two degrees. The outer wall of the annular metal sealing ring provided by wall 21 is also similarly downwardly tapered preferably at an angle of approximately two degrees. It has been found that a taper of about two degrees in the sealing ring inner and outer surfaces of the present invention provides a desired surface seal between the sealing ring and mandrel.

Spacer means associated with the channel of the annular sealing means for limiting the movement of such sealing means within the casing, in the exemplary embodiment of FIGS. 1 through 4, is provided by the annular metal spacer ring indicated generally at 24. Such spacer ring has a generally L-shaped cross section with a longer wall portion 25 and the shorter wall portion 26. The radius of the annular longer wall portion 25 approximates that of the annular channel formed by walls 21 and 22 in the annular sealing ring 2t), and is of a height greater than the depth of such channel so that a part of wall 25 protrudes from within the channel. As shown in FIGS. 1 through 3, the shorter annular wall 26 disposed at generally right angles to the longer wall 25 is spaced above the annular metal sealing ring 20 by wall 25 and below a retainer means. As best seen in FIGS. 2 and 3, the combined axial height of the spacer ring and the bight portion of the sealing ring into which the spacer ring is assembled is less than the axial height of the recess 34 allowing limited axial movement of the assembled spacer ring and sealing ring during movement of the mandrel relative to the casing as hereinafter more fully described.

Annular seal retainer means for mounting within the casing adjacent the sealing means to retain it within the casing 10 when the casing 10 is moved relative to the man-drel 11 is provided in the exemplary embodiment of FIGS. 1, 2, 4 by an annular metal retainer ring, indicated generally at 30. The annular metal retainer ring is provided with a head portion 31 having a cha'mfered bore 32 to align with the bore 32 of the prior casing 10'. A depending annular wall portion 33 has a recess 34 and a mandrel receiving bore 35. The mandrel receiving bore 35 is of the same diameter as bore 12 of the casing 10, while the recess 34 is of a larger diameter to receive the metal sealing ring. The flat or seat 36 in the retainer ring, indicated genera-11y at 30 between the bore 35 and recess 34 may be of the same width as the bottom surface 27 of the sealing ring, indicated generally at 20. The sealing ring therefore may be inserted within the recess 34 in the retainer ring with only so much of the inner wall protruding into the bore 12 of casing 10 as is provided by the taper of inner wall 22. As subsequent-1y described, the taper of outer wall 21 may not effect the metal-to-metal interference between the metal seal 20 and the mandrel 11 due to elastic deformation of wall 21 upon its assembly to the casing recess.

The method of effecting a fluid type surface seal between casing 10 and mandrel 11, in accordance with the present invention, is accomplished as follows. The annular metal seal retaining ring, indicated generally at 30, is initially inverted to the position shown in FIG. 4 to present recess 34 opening upwardly to receive the metal spacer ring 24. The spacer ring 24 is then selectively placed within the recess 34, which is to provide an internal recess in the oil well casing 10, with the shorter wall 26 lying on the flat or seat 36 of retainer 30. The outer diameter of wall 26 is slightly less than the inner diameter of recess 34 to allow a loose fit therein. Wall 26 fitting Within recess 34, serves to selectively position or locate the annular metal longer wall 25 within recess 34 to receive the metal sealing ring, indicated generally at 20. The annular metal sealing ring, as shown in FIG. 4, is then inverted and press fitted over the annular wall 25 of spacer ring 24. Since the bottom surface 27 is of approximately the same width and inner and outer diameters as the fiat or seat 36 in the retainer ring, there is interference between the outer wall 21 of the sealing ring and the recess 34 in the retainer ring. In the preferred embodiment, the outer surface of outer wall 21 is provided with a taper of approximately two degrees, such that it is elastically deformed (deformed within the elastic limit) on fitting within the annular recess 34. The sealing ring is forced down over the spacer ring 24 until most of the wall 25 of the spacer ring has been received in the annular channel formed by walls 21 and 22 of the sealing ring. This is accomplished when the bottom surface 27 of the .sealing ring is approximately level with the bottom surface 37 of the retainer.

The assembled sealing rin indicated generally at 20; spacer ring, indicated generally at 24; and retainer ring, indicated generally at 30'; rare then placed right side up within the casing as shown in FIGS. 1 through 3. The assembly of the metal sealing ring to the casing is thus greatly facilitated by the pre-assembly of the sealing ring, spacer ring and retainer prior to insertion in the casing 10. The retainer, indicated generally at 30, may be threaded to screw into the casing 10' or, as shown in FIGS. 1 through 3, merely be confined within the casing by the abutment with the next casing section 10".

The casing 10 with the metal seal assembly, including the metal sealing means, contained in a recess therein is then run over an inner casing or mandrel member having an outer diameter less than the bore of the casing, but greater than the smallest undeformed inner diameter of the inner wall of the annular metal sealing ring. In the exemplary embodiment, as shown in FIG. 1, the outer diameter of mandrel member 11 is less than the diameter of bore 12 to allow the mandrel to fit within casing 10. However, since bottom surface 27 of the sealing ring, indicated generally at 20, is approximately equal to the fiat or seat 36 of the retainer ring, wall 21 protrudes into the bore 12 of casing 10 due to its taper. The smallest inner diameter of the metal sealing ring occurs at the upper edge of inner wall 22. Preferably, in accordance with the present invention, the outer diameter of mandrel 11 equals the inner diameter of wall 22 at a point thereon approximately midway between the bottom and the top of wall 22. Put another way, the inner diameter of Wall 22 varies from approximately the diameter of bore 12 at the bottom to a smaller diameter at the top of wall 22 due to the taper of wall 22. It has been found that a taper of about two degrees on the outer wall of the sealing ring, when used with conventional casing and mandrel members in oil well drilling and producing operations, produces an interference between wall 22 and mandrel 11 such that a surface seal rather than a mere lip seal is effected therebetween. It is specifically contemplated within the present invention that the seal effected is a surface seal along at least a third of the wall 22 as opposed to a mere lip seal or theoretical line contact between the top edge of wall 22 and mandrel 11. Thus, inner wall 22, according to the present invention, is deformed within its elastic limit against the mandrel to effect the surface seal therebetween upon the running of the casing 10 over mandrel 11 without the application of additional external or internal sealing forces or pressures. Such surface seal is shown in FIG. 2.

As the casing is run down over the inner casing or mandrel member elastically deforming the inner wall of the metal sealing ring against the outer wall of the inner casing or mandrel member, it is contemplated within the present invention that the metal .sealing means be spaced from overhead portions of the recess within the casing against which the sealing means might abut and interfere with. As shown in FIG. 2, casing 10 has been almost completely run down over the inner casing or mandrel member 11 and the inner wall 22 of the metal sealing ring has been elastically deformed to provide a sunface seal against the mandrel 11. As the mandrel member 11 passes through the annular metal sealing ring elastically deforming the inner wall 22, it imparts an upward force to the sealing ring which might cause it to ride upward within the recess 34 within casing 10 until inter ference occurred between the free ends of the sealing ring channel walls 21 and 22 and the overhead portion 38 of the recess. Such interference between the elastically deforming inner Wall 22 of the sealing ring with the overhead portion 38 of the recess 34- is to be avoided since it may cause deformation of Wall 22 beyond its elastic limit and consequent premature deterioration of the seal as well as perhaps immediate breaking of the surface seal being effected between wall 22 and mandrel member 11. Therefore, in accordance with the method of the present invention, concurrently with the step of running the casing over the mandrel and deforming the sealing means elastically, spacing of the divergent walls of the sealing ring from the overhead portion of the recess is ptovided. In the exemplary embodiment of apparatus, shown in FIGS. 1 through 4, for effecting the seal according to the present method, the spacer ring, indicated generally at 24, spaces the sealing ring from the overhead portion 38 during the running of the casing over the mandrel. As shown in FIGS. 2 and 3, the combined height of the assembled spacer ring, indicated generally at 24, and the sealing ring, indicated generally at 20, is less than the height of the recess 34. As mandrel 10 engages the sealing ring, deforming the inner wall 22 elastically, upward movement of the sealing ring is arrested after an initial movement thereof due to the abutment of the shorter leg 26 of the spacer ring with the overhead portion 38. An upward force upon the sealing ring is thus transmitted to the longer annular leg or wall 25 of the spacer ring and through the shorter annular leg or wall 26 to the retainer. Annular wall 25 is provided with a bottom radius approximating that of the bottom radius of the channel formed in the sealing ring by walls 21 and 22 to allow transmission of load therebetween without effecting the free deformation of the walls 21 and 22 during the afo-redescribed operations.

An alternative exemplary embodiment of apparatus to effect a fluid tight surface seal according to the method of the present invention is shown in FIGS. 5 through 8. Referring first to FIG. 5, a casing 40 is shown with an alternative exemplary embodiment of metal seal, indicated generally :at 50 contained in a recess therein prior to the complete running of the casing down over an inner casing or mandrel member 41. In this embodiment, the recess within the casing 40 is formed in an inner wall of the casing at 64.

Annular metal sealing means for mounting within the recess within the casing 40, recessed relative to the casing bore 42, is provided in the alternative exemplaiy embodiment of FIGS. 5 through 8 by the annular sealing ring, indicated gene-sally at 50. As in the prior embodiment of FIGS. 1 through 4, the annular metal sealing ring, indicated generally at 5%), is provided with upwardly opening spaced divergent inner and outer walls 52 and 51, respectively interconnected by a bight portion 53. Inner and outer walls 52 and 51, as in the prior embodiment, are tapered downwardly, preferably at an angle of approximately two degrees, and form an annular upwardly opening channel therebetween in the sealing ring.

Spacer means associated with the channel of the annular sealing means for limiting the movement of the sealing means within the casing recess when the casing is run over the mandrel member in this alternative exemplary embodiment comprises the annular spacer ring 54. Spacer ring 54, as in the prior embodiment, is provided with a height greater than the depth of the channel formed in the annular metal sealing ring to protrude therefrom a distance sufficient to space the sealing ring from an overhead portion of the recess within casing 40 when assembled therein.

Annular seal retainer means for mounting within the casing adjacent the sealing means to retain it within the casing during relative movement of the casing to the mandrel, in the alternative exemplary embodiment, cornprises the annular meta-l retainer ring 60. Retainer ring 649 is provided with an outer diameter slightly less than that of recess 64 and is adapted to loosely slide within an enlarged bore 43 within casing 40 to the recess 64. It may be seen in FIG. 7, that mandrel member 41 is mu'lti-diameter with an upper portion of a diameter slightly less than that of the bore 42 of casing 40 and a larger diametered lower portion having a diameter slightly less than the enlarged bore portion 43 of casing 10. Positioning pins 62 in the head portion 61 of retainer 60 are provided to slideably mount retainer 60 within the enlarged bore portion 43 of casing 40. As shown in FIG. 5, for example, a channel 44 may be provided in the bore 43 of casing 40 to receive the plurality of pins 62 after the retainer ring 60 has been assembled to the casing in accordance with the present method. Further, in this exemplary embodiment annular seal retainer ring 60 includes a downwardly facing mandrel guide means to guide the mandrel 41 through the annular sealing means upon running of the casing over the mandrel. Such guide means includes the provision of the downwardly facing and tapered surface 63 on tail portion 64 to receive and guide the mandrel member 41 through the retainer and into aligned engagement with the annular metal sealing ring thereabout.

In accordance with the method of the present invention, with the casing 40 inverted, the annular metal spacer ring 54 is placed within the internal recess 64 in the oil well casing 40 in a selected, generally centered location within recess 64. The outer diameter of ring 54 is less than the diameter of the recess 64 to allow the positioning of outer wall 52 of the sealing ring therebetween. Next, the annular metal sealing ring, indicated generally at 50, is inverted and press fitted into the recess 64 over the annular metal spacer ring 54, as previously described with regard to the prior embodiment, elastically defonming the outer wall 52 of the sealing ring against the side wall of recess 64.

Annular metal retaining ring 60 is then inverted and assembled within the easing into alignment with channel 44 and the plurality of pins 62 are inserted to hold the retainer ring within the casing while allowing limited vertical sliding movement thereof below the sealing ring indicated generally at 50. When the casing is in upright position as shown in FIG. 5, the retainer ring 60, because of its loose mounting within the casing, rides therein :below and spaced from the annular sealing ring indicated generally at 50 with the pins 62 bearing on bottom surfaces of channel 44.

The casing 40 with the material seal assembly contained in a recess therein, is then run down over the inner casing or mandrel member 41. If mandrel 41 is not in exact alignment with bore 61 of retainer 60, the guide surface 64 will direct the mandrel through the bore 61 to the annular sealing means indicated generally at 50. During such guiding of the mandrel member by the retainer 61 it may slide upwardly with the casing until it abuts the bottom of the sealing means. As the mandrel penetrates the bore of the sealing means elastically deforming the inner wall 51 of the sealing ring, as previously described, the sealing ring end spacer will tend to ride upwardly within recess 64.

According to the present method, concurrently with the running of the casing down over the inner casing or mandrel member, elastically deforming the inner wall of the metal sealing ring against the outer wall of the inner casing or mandrel member, the metal sealing means is spaced from overhead portions of the recess within the casing by metal spacer means. In FIG. 6, the casing is shown completely run down over the inner casing or mandrel member 41 with the divergent walls 51 and 52 of the sealing ring being spaced from the overhead portion 68 of recess 64 by the spacer ring 54. Since retainer ring 60 is under no load at this time, it merely comes to rest upon the mandrel member 41 with its tapered surface 63 abutting a chamfered portion of the mandrel member between its larger and smaller diameters.

Upon the backing off of casing 40 from the mandrel 41, as shown in FIG. 7, the frictional forces on the exemplary sealing ring, shown generally at 50, are reversed causing it to move downwardly relative to casing 41). In FIG. 7 the exemplary metal sealing ring is shown immediately after its contacting the retainer ring prior to relative movement between retainer ring 60 and mandrel 41. Upon further relative movement between the casing and mandrel with the backing off of casing 40, the pins 62 of retainer ring 60 engage the lower surface of channel 44, retaining the annular sealing ring and annular spacer ring within recess 64 upon the complete backing off of the casing 40.

It may be seen from the foregoing detailed description of the method and two exemplary embodiments of apparatus according to the present invention that an effective high pressure fluid tight surface seal may be effected between an outer casing and an inner casing or mandrel member merely upon the running of the casing member down over the mandrel member. The seal of the present invention has been tested to 15,000 psi. with no permanent deformation that would affect its continued use. Because of the seals unique construction, and mode of operation, it can be formed of materials having low tensile strength such as stainless steel or hastelloy C. The metal seal effected is reusable indefinitely, is easily assembled within an oil well casing and does not require the application of additional external or internal forces or sealing pressures. It is thus a truly self-energizing seal. The novel method of effecting the aforedescribed seal including the orienting and spacing of the sealing means insures its continued uninterrupted use without deterioration due to uneven wearing of over-deforming the sealing means to cause a permanent set in the metal and consequent failure of the metal seal to operate effectively.

It should be understood that the foregoing detailed explanation of the exemplary embodiments and the method of the present invention are exemplary in nature and not intended to limit the invention in any way from covering alternative or equivalent embodiments and methods embodying the invention. For example, it is contemplated that the spacer means associated with the annular sealing means may be provided as an integral portion of the sealing means, as by a centrally positioned wall member extending upwardly above the sealing ring walls or an extension of part of the outer sealing ring wall itself. Further, the taper provided between the inner wall of the sealing ring and the mandrel member could be provided by a tapered recess receiving a sealing ring having non-tapered walls. The present invention is limited only and defined by the following claims.

I claim: 1. A metal seal assembly assembled within a casing recess to effect a fluid tight seal between a casing and a mandrel upon running of the casing over the mandrel without the application of additional external or internal sealing pressures which is resistant to deterioration in subsea applications, said metal seal assembly comprising: annular metal sealing means for mounting within said casing recess, said sealing means having spaced divergent channel Walls interconnected by a bight portion to define an annular channel therein;

annular metal spacer means received in said sealing means annular channel having a height greater than said channel for limiting movement of said sealing means within said casing recess when said casing is run over a mandrel and for spacing free ends of said divergent walls from overhead portions of the casing recess overlying said free ends the combined axial height of said sealing means and spacer means received therein being less than the axial height of said recess; and

annular metal retainer means for mounting within said casing adjacent said recess to retain said sealing means and spacer means within said casing when said casing is moved relative to said mandrel.

2. A metal seal assembly assembled within a casing recess having a predetermined axial height and inner surface diameter to effect a fiuid-tight seal between a casing and a mandrel run therein, said assembly comprising:

a resilient annular metal sealing ring to be mounted within said casing recess including an elastically deformable outwardly tapered outer wall to be elastical- 1y deformed by abutment with said recess inner surface on assembly of said ring Within said recess, an elastically deformable radially inwardly tapered inner wall for elastically deformed sealing engagement about a mandrel run therein and a bright portion connecting said inner and outer walls and forming therewith an annular channel opening in an axial direction within said recess when said ring is mounted within said recess; and

a spacer ring to be received in said sealing ring channel between said sealing ring inner and outer walls on said bight portion, the axial height of said spacer ring being greater than the depth of said channel, and the combined axial height of said spacer ring and sealing ring bight portion being less than the axial height of said recess.

3. A metal seal assembly assembled within a casing to effect a fluid-tight seal between the casing and a mandrel on running of the casing over the mandrel which is not dependent in its operation upon external application of sealing pressures or internal casing hydraulic pressures, said assembly comprising:

annular sealing means for mounting within a recess within a casing, said sealing means being recessed relative to the casing bore and having an upwardly opening annular channel;

spacer means associated with said sealing means for allowing limited axial movement of said sealing means within said casing and for preventing engagement of said sealing means with an upper wall of said recess; and

annular seal retainer means for mounting within said casing adjacent said sealing means to retain said sealing means within said casing, said retainer means including a downwardly facing mandrel guide means to guide said mandrel through said annular sealing means upon running of said casing over said mandrel.

References Cited by the Examiner UNITED STATES PATENTS SAMUEL ROTHBERG, Primary Examiner. 

1. A METAL SEAL ASSEMBLY ASSEMBLED WITHIN A CASING RECESS TO EFFECT A FLUID TIGHT SEAL BETWEEN A CASING AND A MANDREL UPON RUNNING OF THE CASING OVER THE MANDREL WITHOUT THE APPLICATION OF ADDITIONAL EXTERNAL OR INTERNAL SEALING PRESSURES WHICH IS RESISTANT TO DETERIORATION IN SUBSEA APPLICATIONS, SAID METAL SEAL ASSEMBLY COMPRISING: ANNULAR METAL SEALING MEANS FOR MOUNTING WITHIN SAID CASING RECESS, SAID SEALING MEANS HAVING SPACED DIVERGENT CHANNEL WALLS INTERCONNECTED BY A BIGHT PORTION TO DEFINE AN ANNULAR CHANNEL THEREIN; ANNULAR METAL SPACER MEANS RECEIVED IN SAID SEALING MEANS ANNULAR CHANNEL HAVING A HEIGHT GREATER THAN SAID CHANNEL FOR LIMITING MOVEMENT OF SAID SEALING MEANS WITHIN SAID CASING RECESS WHEN SAID CASING IS RUN OVER A MANDREL AND FOR SPACING FREE ENDS OF SAID DIVERGENT WALLS FROM OVERHEAD PORTIONS OF THE CASING RECESS OVERLYING SAID FREE ENDS THE COMBINED AXIAL HEIGHT OF SAID SEALING MEANS AND SPACER MEANS RECEIVED THEREIN BEING LESS THAN THE AXIAL HEIGHT OF SAID RECESS; AND ANNULAR METAL RETAINER MEANS FOR MOUNTING WITHIN SAID CASING ADJACENT SAID RECESS TO RETAIN SAID SEALING MEANS AND SPACER MEANS WITHIN SAID CASING WHEN SAID CASING IS MOVED RELATIVE TO SAID MANDREL. 